Network coverage hole detection

ABSTRACT

A technology for a user equipment (UE) that is operable to connect to a third generation partnership project (3GPP) long term evolution (LTE) cell in a cellular network. Logged minimization of drive test (MDT) measurements can be recorded at the UE at a selected rate when the UE is in a radio resource control (RRC) idle mode in a first LTE cell in a cellular network. A change in a UE state of the RRC idle mode can be identified. The Logged MDT measurements can stop being recorded at the UE when the UE state changes from a camped normally UE state to another UE state of the RRC idle mode. The Logged MDT measurements can resume being recorded when the UE state changes to the camped normally UE state of the RRC idle mode.

RELATED APPLICATIONS

This application claims the benefit of and hereby incorporates byreference U.S. Provisional Patent Application Ser. No. 61/859,121, filedJul. 26, 2013.

BACKGROUND

When deploying a Radio Access Technology (RAT) in a communicationsnetwork, coverage planning can be a complex task for operators becauseof environmental conditions, interference from other networks ordevices, and so forth. Avoiding coverage holes in cellular networks whenplanning cell locations can be difficult. Coverage detection andoptimization processes can be used to detect coverage holes in cellularnetworks.

Traditionally, coverage detection is performed through drive tests wherea motor vehicle equipped with mobile radio equipment drives around incellular networks measuring different network coverage metrics. Thecoverage measurements are then processed by radio experts for networkcoverage optimization. Network coverage can be optimized by tuningnetwork parameters such as a transmission power of a node or antennaorientations and tilts. The use of drive tests can involve largeOperational Expenditure (OPEX), delays in detecting the problems, andmay not offer a complete and reliable picture of the network coverage.Additionally, the drive tests are limited to areas accessible by motorvehicles, such as roads. Drive tests are not helpful in detectingcoverage problems inside buildings, off-road environments, or otherareas not accessible to motor vehicles.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the disclosure will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the disclosure; and, wherein:

FIG. 1 depicts a coverage hole between a third generation partnershipproject (3GPP) long term evolution (LTE) node and another 3GPP LTE nodein accordance with an example;

FIG. 2A depicts minimization of drive test (MDT) measurements taken byUE in accordance with an example;

FIG. 2B depicts minimization of drive test (MDT) measurements taken byUE as the UE moves through a 3GPP LTE coverage hole in accordance withan example;

FIG. 3 shows that the user equipment (UE) can collect Logged MDTmeasurements at trigger events in accordance with an example;

FIG. 4 shows sending MDT configuration information from an elementmanager (EM) to an enhanced Node B (eNode B) in accordance with anexample;

FIG. 5 shows a table of parameters of an information element (IE) forthe CCO SON in a MDT configuration in accordance with an example;

FIG. 6 shows a table of parameters of an IE for the CCO SON in a MDTconfiguration in accordance with an example;

FIG. 7 shows a table of parameters of an IE for the CCO SON in a MDTconfiguration in accordance with an example;

FIG. 8 shows a table of parameters of an IE for the CCO SON in a MDTconfiguration in accordance with an example;

FIG. 9 shows a framework for configuring a UE with a Logged MDT inaccordance with an example;

FIG. 10 shows programming code used to modify a logged measurementconfiguration RRC message in accordance with an example;

FIG. 11 shows a framework for configuring a UE with a Logged MDT inaccordance with an example;

FIG. 12 shows programming code used to modify an inter radio accesstechnology (RAT) cell reselection detection message in accordance withan example;

FIG. 13 shows a framework for a UE to send a UE information response RRCmessage to an eNode B in accordance with an example;

FIG. 14A shows an exemplary embodiment of programming code used tomodify a UE information response message in accordance with an example;

FIG. 14B shows an exemplary embodiment of programming code used tomodify a UE information response message in accordance with an example;

FIG. 14C shows an exemplary embodiment of programming code used tomodify a UE information response message in accordance with an example;

FIG. 15A shows another exemplary embodiment of programming code used tomodify a UE information response message in accordance with an example;

FIG. 15B shows another exemplary embodiment of programming code used tomodify a UE information response message in accordance with an example;

FIG. 15C shows another exemplary embodiment of programming code used tomodify a UE information response message in accordance with an example;

FIG. 16 shows a table of trace-based MDT reporting parameters to informa trace collection entity (TCE) about MDT measurements that werecollected by a UE in a CCO SON in accordance with an example;

FIG. 17 depicts the functionality of another computer circuitry with aUE operable to connect to a 3GPP LTE cell in a cellular network inaccordance with an example;

FIG. 18 depicts a method to record MDT measurements at a UE in acellular network in accordance with an example;

FIG. 19 depicts a UE for use in a communications network in accordancewith an example; and

FIG. 20 illustrates a diagram of a user equipment (UE) in accordancewith an example.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

Before the present invention is disclosed and described, it is to beunderstood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular examples only and is not intended to be limiting. The samereference numerals in different drawings represent the same element.Numbers provided in flow charts and processes are provided for clarityin illustrating steps and operations and do not necessarily indicate aparticular order or sequence.

Cellular network providers desire to provide optimal cellular coveragefor users of the cellular network services. Previously, cellular networkproviders deployed universal mobile telecommunications system (UMTS)nodes and/or high speed packet access (HSPA) nodes to provide coverageto the users of the cellular network. More recently, third generationpartnership project (3GPP) long term evolution (LTE) coverage has beendeployed by cellular network providers to increase the performance ofcellular networks, such as increasing data communication capacity anddata transfer speeds. In some areas within the cellular networks of theservice providers, 3GPP LTE coverage is sporadic or intermittent, e.g.there are holes in the 3GPP LTE network coverage. For example, acellular network of a service provider can offer continuous orcomprehensive network coverage at an underlying UMTS/HSPA layer of anetwork while offering limited or sporadic coverage at a 3GPP LTE layerof the network.

In cellular communications, a coverage hole is an area in which thesignal strength of a cellular network experienced by a user equipment(UE) is insufficient to maintain connectivity and there is no coveragefrom an alternative 3GPP LTE cell. For example, a coverage hole can anarea where a signal to noise ratio (SNR) or a signal to interferenceplus noise ratio (SINR) of a serving and neighboring cells, such as 3GPPLTE cells, is below a threshold level to maintain basic service.Coverage holes can be caused by physical obstructions (such as newbuildings and hills), unsuitable antenna parameters, or inadequate radiofrequency (RF) planning. A multiple band (multi-band) and/or multipleradio access technology (multi-RAT) UE can switch to another band or RATwhen a coverage hole is detected.

Coverage holes can exist in a single cell or node of a cellular networkor in the vicinity of a border between adjacent cells, i.e. a cell edge.At a cell edge, a UE or a network can perform a handover process to movethe UE from one cell to another cell in the cellular network. A handoverof the UE from one cell to another may fail because of the coverageholes between the cells. Coverage holes can also occur between differenttypes of cells or nodes in a cellular network. For example, when a UE ismoving within the cellular network, the UE may initially be incommunication with a 3GPP LTE node and then move outside of the 3GPP LTEnode coverage. When there is not 3GPP LTE coverage for a location wherethe UE is located, the UE may search for another node within thecellular network, such as a UMTS node, and switch to the other node. Thearea where there 3GPP LTE node does not provide 3GPP LTE coverage to theUE can be a coverage hole for the 3GPP LTE network within the cellularnetwork.

FIG. 1 depicts a coverage hole 130 between two 3GPP LTE nodes, referredto as a 3GPP LTE A node 110 and a 3GPP LTE B node 120. FIG. 1 also showscoverage areas for two UMTS nodes, UMTS A node 140 and UMTS B node 150.The region between the coverage areas of the 3GPP LTE A node 110 and the3GPP LTE B node 120 is at the cell edge of 3GPP LTE A node 110 and 3GPPLTE B node 120 and does not provide a region where a UE can have 3GPPLTE network coverage, e.g. a coverage hole 130. When a UE leaves thecoverage area of the 3GPP LTE A node 110 and enters the coverage hole130, and before entering the coverage area of the 3GPP LTE B node 120,the UE can switch to a UMTS node, e.g. UMTS A node 140 or UMTS B node150.

In one embodiment, to determine coverage holes in a cellular network,the cellular network can use a minimization of drive test (MDT)measurement. In one embodiment, the MDT measurement can be used for a UEusing an intra-RAT mode, i.e. when a UE switches between two nodes thatare the same type of node, with the same RAT. For example, a UE thatswitches from one UMTS node to another UMTS node is using an intra-RATmode. In another embodiment, the MDT measurement can be used for a UEusing an inter-RAT mode, i.e. when a UE switches between two nodes thatare different types of RATs. For example, a UE that switches from a 3GPPLTE node to a UMTS node is using an inter-RAT mode.

In one embodiment, a UE can have an MDT configuration that isRAT-specific. The MDT configuration can be used to configure the UE totake MDT measurements. The MDT measurements can include radiomeasurements and location information of the UE. One advantage of thecellular network using MDT measurements to determine cellular networkcoverage and coverage holes can be to assess network performance whilereducing an Operational Expenditure (OPEX) associated with usingtraditional drive tests to determine cellular network coverage andcoverage holes. In one embodiment, a network operator can request theUEs perform and report specific radio measurement and/or Quality ofService (QoS) measurements associated with the location of the UE.

In one embodiment, to increase network performance and flexibility andreduce capital expenditures and operational expenditures, aself-organizing network (SON) can be used in a 3GPP network. A SON of a3GPP network can have self-organizing capabilities for automating theconfiguration and optimization of the wireless network by introducingfunctionalities of self-configuration, self-optimization, andself-healing. Self-configuration provides the capabilities for newlydeployed eNode Bs in the cellular network to finish the configurationwith automatic installation procedures for obtaining the basicconfiguration information to operate the system. Self-configurationprocedures can include automatic configuration of physical cellidentity, neighbor-list configuration, and coverage and capacityparameters.

A coverage and capacity optimization (CCO) function can be used bymobile network operators (MNOs) to reduce OPEX by automating themaintenance and optimization of a coverage and capacity of the network.In one embodiment, a CCO function can be used to monitor networkcoverage and capacity performance, automatically detect problems in thenetwork, and take selected actions or notify the operator when anoperator action may be needed to fix the problem. In one embodiment, aUE can take MDT measurements and an eNode B can use the MDT measurementsto monitor network performance and coordinate a cellular networkoptimization procedure.

In one embodiment the MDT measurements can be Immediate MDTmeasurements. An Immediate MDT measurement can be taken when a UE is ina radio resource control (RRC) connected state. When a UE takesImmediate MDT measurements, the MDT measurements can be reported atapproximately the time that the MDT measurements are taken. In oneembodiment, the Immediate MDT measurements can be configured using RRCsignaling procedures for radio resource management (RRM) measurements.The Immediate MDT measurements can be reported using RRM measurementreporting procedures.

In another embodiment the MDT measurements can be Logged MDTmeasurements. A Logged MDT measurement can be taken when a UE is in anRRC idle state. The UE can receive an MDT configuration using RRCsignaling while the UE is in an RRC connected state. The MDTconfiguration can remain valid during an RRC idle state and/or when theUE switches between RRC idle states and RRC connected states. In oneembodiment, the MDT configuration for the Logged MDT can remain validwhile a UE resides in another RAT.

In one embodiment, Logged MDT measurements can be taken by collectingMDT measurement data, storing the MDT measurement data at the UE, andcreating a log file of the MDT measurement data at the UE. The log filecan be communicated from the UE to the network, such as to a node orserver in an evolved universal terrestrial radio access network(E-UTRAN) network. In one embodiment, the log file can be communicatedto the node or server when the UE returns to an RRC connected state andthe node or server requests the log file. For example, when the UEreturns to an RRC connected state the node or server can use RRC messagepairs, a UE information request and a UE information response, torequest the log file.

Traditionally, to determine coverage holes, a UE is configured tocontinuously report data to the network. The network can thencommunicate the reported data to a trace collection entity (TCE), suchas an MDT server, and the TCE can filter and analyze the data at a laterpoint in time to determine coverage holes.

One advantage of using MDT measurements, such as Logged MDTmeasurements, can be to decrease the amount of data communicated fromthe UE to the network. A decrease in the amount of data can decrease theprocessing time and processing power needed to determine coverage holes.Another advantage of using MDT measurements, such as Logged MDTmeasurements, to determine coverage holes can be to minimize the numberand/or size of measurements taken to determine coverage holes. When aminimal number and/or size of measurements is taken, the decreasednumber and/or size of the measurements can increase the battery life ofa UE, reduce data traffic communicated in a network, and reduce thememory storage requirements of the UE to store the MDT measurement, suchas the Logged-MDT measurements.

Traditionally, a UE is configured to continuously collect data samples,such as downlink signal strength measurements, to use for coverage holedetermination. In one embodiment, the UE can take MDT measurementsduring selected periods of time. FIG. 2A shows MDT measurements 240taken by UE 230 as it moves through cells on a UE trajectory. The UE 230can initially take periodical or continuous MDT measurements 240 whilethe UE 230 is located in Cell A 210, wherein Cell A 210 is a cell with3GPP LTE coverage and UMTS coverage. When the UE 230 switches to a cellwith no 3GPP LTE coverage, such as Cell D 220, the UE 230 is configuredto pause or stop taking MDT measurements 250. When the UE 230 moves toanother cell with 3GPP LTE coverage, such as Cell C 260, the UE 230 isconfigured to resume periodically or continuously taking MDTmeasurements 240. FIG. 2B shows MDT measurements 240 taken by UE 230 asit moves through cells on a UE trajectory and a pause or stopping oftaking MDT measurements 250 as the UE 230 moves through a 3GPP LTEcoverage hole. FIG. 2B is the same as FIG. 2A in all other regards. Inone embodiment, the UE can pause taking MDT measurements when the UEleaves a cell with 3GPP LTE coverage and resume taking MDT measurementswhen the UE returns to the same cell with 3GPP LTE coverage. In anotherembodiment, coverage holes can be detected by identifying a pattern astopping and resuming of MDT measurements. In another embodiment, a sizeor a boundary of the coverage hole can be determined by the locationwhere the UE stops taking the MDT measurements and the location wherethe UE resumes taking the MDT measurements.

In another embodiment, the UE can take MDT measurements at selectedevents. FIG. 3 illustrates that the UE 330, traveling along a UEtrajectory, can collect Logged MDT measurements at trigger events 320and 340. The trigger events 320 and 340 can include: the UE switchingfrom a 3GPP LTE node 310 to a non-3GPP LTE node 350, such as a UTMSnode; the UE switching from a non-3GPP LTE node 350 to a 3GPP LTE node310 or 360; the UE leaving a cellular network, such as when the UEenters an area not covered by the network; and when the UE returns to acellular network, such as when the UE returns to an area covered by thenetwork.

One advantage of collecting Logged MDT measurements at a trigger eventcan be to reduce or minimize the number of data measurements taken todetermine coverage holes. For example, when a trigger event does notoccur, the UE does not take any MDT measurements to determine coverageholes. In another example, when a trigger event occurs, the UE can takeindividual MDT measurements when the trigger event occurs.

Another advantage of collecting Logged MDT measurements at a triggerevent can be to increase the number of MDT measurements a UE can storein a memory of the UE. For example, where the UE takes Logged MDTmeasurements when a trigger event occurs, the UE can store an decreasednumber of MDT measurements to be used for coverage hole determinationcompared to continuously taking data measurements for the same period oftime and/or for the same number of coverage holes.

In one embodiment, for a trace-based MDT configuration, at least one newparameter can be used to configure and control CCO SON operations in aUE, i.e. detecting inter-RAT cell reselection events. FIG. 4 showssending MDT configuration information from an element manager (EM) 410to an eNode B 440. In one embodiment, a trace session activation messagecan include MDT configuration information. FIG. 4 shows that the tracesession activation message, which includes MDT configurationinformation, can be sent from an EM 410 to a home subscriber server(HSS) 420. The HSS 420 stores trace control and configurationinformation and sends insert subscriber data, which includes MDTconfiguration information, to a mobility management entity (MME) 430.The MME 430 stores trace control and configuration parameters and sendsa trace start message, which includes MDT configuration information, tothe eNode B 440. In one embodiment, the MDT configuration of the tracestart message can include S1 application protocol (S1AP).

FIGS. 5 and 6 show a table of parameters of an IE for the CCO SON in anMDT configuration. FIG. 6 is a continuation of the table in FIG. 5.FIGS. 5 and 6 further show the IE for the CCO SON that can be used aspart of a Logged MDT configuration. Additionally, FIG. 6 shows a tablewhere the S1AP includes a parameter to turn a CCO SON measurement on andoff. In one embodiment, the S1AP can include information on the expectedactions taken by the UE when the UE receives the S1AP information. Forexample, the S1AP can include information on whether the UE will take areference signal received power (RSRQ) measurement or a reference signalreceived power (RSRP) measurement. In another embodiment, the S1AP caninclude trigger event information to configure the UE to take MDTmeasurements at selected periods of time, such as logging intervalconfiguration information. In one embodiment, the S1AP can includetrigger threshold values. In another embodiment, the S1AP can includetrigger event information to configure the UE to take MDT measurementsat selected trigger event.

In one embodiment, the selected trigger event can be an inter-RAT cellreselection trigger event. For example, the inter-RAT cell reselectiontrigger event can be when a UE in RRC idle mode changes from a campednormally mode to a camped on any cell mode, e.g. the UE moves from anLTE cell to a UMTS cell. In another example, the inter-RAT cellreselection trigger event can be when a UE in RRC idle mode changes froma camped on any cell mode to a camped normally mode, e.g. the UE returnsfrom a non-LTE cell to an LTE cell.

In one embodiment, the selected trigger event can be an LTE coveragehole detection trigger event. For example, the LTE coverage holedetection trigger event can be when a UE in RRC idle mode changes from acamped normally mode to an any cell selection mode, e.g. the UE movesfrom an LTE cell to a coverage hole. For example, the LTE coverage holedetection trigger event can be when a UE in an RRC idle mode changesfrom an any cell selection mode to a camped normally mode, e.g. a UEreturns to an LTE cell.

In one embodiment, coverage holes, such as LTE coverage holes, can bedetected using LTE inter-RAT cell reselection measurements, includingLogged MDT UE measurements such as RSRP measurements and/or RSRQmeasurements. In one embodiment, the RSRP measurements or the RSRQmeasurements can include cell identification (Cell ID) informationand/or location information. In another embodiment, the RSRPmeasurements or the RSRQ measurements can include trigger eventinformation such as when a UE in RRC idle mode changes from a campednormally mode to a camped on any cell mode or when the UE changes from acamped on any cell mode to a camped normally mode. In one embodiment,the UE can communicate location information to an eNode B, network node,or network server when an LTE inter-RAT cell reselection event occurs.

In one embodiment, coverage holes, such as LTE coverage holes, can bedetected using LTE coverage hole detection, including Logged MDT UEmeasurements such as an RSRP measurement or an RSRQ measurement. In oneembodiment, the RSRP measurement or the RSRQ measurement can includecell identification (Cell ID) information and/or location information.In another embodiment, the RSRP measurement or the RSRQ measurement caninclude trigger event information such as when a UE in an RRC idle modechanges from a camped normally mode to an any cell selection mode orwhen the UE changes from an any cell selection mode to a camped normallymode. In one embodiment, the UE can be configured to communicatelocation information to an eNode B, network node, or network server whenan LTE coverage hole event occurs.

FIGS. 7 and 8 show another table of parameters of an IE for the CCO SONin a MDT configuration. FIG. 8 is a continuation of the table in FIG. 7.FIGS. 7 and 8 further show the IE for the CCO SON that can be insertedindependently into the CCO SON from existing MDT modes. For example, theIE for the CCO SON in a MDT configuration can be used to configureanother mode of MDT operation, e.g. not an Immediate MDT mode or aLogged MDT mode. Additionally, FIG. 8 shows a table with a set of CCOSON parameters. FIG. 8 further shows an information element (IE) for aCCO SON, such as a single parameter or a container, in the MDTConfiguration IE that is defined in 3GPP TS 36.413 v11.6.0 (December2012).

FIG. 9 shows a framework for configuring a UE with a Logged MDT. The MMEcan send a trace start message that includes MDT configurationinformation to an eNode B, as shown in block 910. The eNode B can storetrace control and configuration parameters, as shown in block 920. TheeNode B can start a trace recording session, as shown in block 930. MDTcriteria can be checked at the eNode B, as shown in block 940. The eNodeB can send a logged measurement configuration RRC message to the UEwhile the UE is in an RRC connected mode, as shown in block 950. In oneembodiment the logged measurement configuration RRC message can be usedby an E-UTRAN to configure the UE to perform logging of MDT measurementresults while the UE is in an RRC idle mode. In one embodiment, the RRCmessage can be used by the E-UTRAN to configure the UE to performlogging of measurement results while in the UE is in an RRC idle mode.MDT criteria checking can be performed at the UE while the UE is in anRRC idle mode, as shown in block 960. MDT measurements can be taken bythe UE, as shown in block 970.

FIG. 10 shows Abstract Syntax Notation (ASN) programming code used tomodify a logged measurement configuration RRC message. The ASN codesection for the CCO SON configuration parameters represents the CCO SONin the MDT Configuration IE, as discussed in the preceding paragraphsfor FIG. 6. The programming code assumes that a signaling radio beareris SRB1, a radio link control service access point (RLC-SAP) is anacknowledged mode (AM) SAP, a logical channel is a dedicated controlchannel (DCCH), and the logged measurement configuration RRC messagedirection is from an eNode B to a UE. The ASN code section for theLoggedMeasurementConfiguration-r10 represents theLoggedMeasurementConfiguration, as discussed in the preceding paragraphsfor FIG. 9.

FIG. 11 shows a framework for configuring a UE with a Logged MDT. TheeNode B can send an inter-RAT cell reselection detection message to theUE while the UE is in an RRC connected mode, as shown in block 1110. TheUE can location stamp the MDT measurement data, as shown in block 1120.The other blocks in FIG. 11 are the same as discussed in the precedingparagraphs for FIG. 9.

FIG. 12 shows ASN programming code used to modify an inter-RAT cellreselection detection message. The ASN code section for the CCO SONconfiguration parameters can be used to detect coverage holes, asdiscussed in the preceding paragraphs for FIG. 6. The programming codeassumes that a signaling radio bearer is SRB1, a radio link controlservice access point (RLC-SAP) is an acknowledged mode (AM) SAP, alogical channel is a dedicated control channel (DCCH), and the loggedmeasurement configuration RRC message direction is from an E-UTRAN to aUE.

In one embodiment, the UE can create an MDT measurement log withlocation information. In another embodiment, the UE can create an MDTmeasurement log with RF fingerprint information when a cell reselectionevent (CRE) is detected. The CRE can include an inter-RAT cellreselection trigger event and/or LTE coverage hole detection triggerevent. The inter-RAT cell reselection trigger event can be when a UE inRRC idle mode moves from a 3GPP LTE cell to a non-3GPP LTE cell, such asa UMTS cell, and vice versa. The LTE coverage hole detection triggerevent can occur when a UE in an RRC idle mode moves from a 3GPP LTE cellto a coverage hole and vice versa.

In one embodiment, the UE can include trace specific details in themeasurement log. The trace specific details can include trace referenceinformation, trace recording session reference information, or tracecollection entity identification (TCE-Id) information. In oneembodiment, the UE can include CRE details in the measurement log. TheCRE details can include a Boolean variable designated as a public landmobile network (PLMN) change. When the PLMN change Boolean variable istrue, the PLMN Change indicates a reselection to a different PLMN. Whenthe PLMN change Boolean variable is false, the PLMN Change indicates areselection within the same PLMN. In one embodiment, the UE can stopcollecting cell reselection event information when a maximum number ofCREs has been reached.

FIG. 13 shows a framework for a UE to send a UE information response RRCmessage to an eNode B. In one embodiment, the UE can send the UEinformation response RRC message to an eNode B based on a request fromthe network. The eNode B can send a UE information request to the UE, asin block 1310. The UE can send a UE information response to the eNode B,as in block 1320. The eNode B can aggregate the MDT measurements fromthe UE, as show in block 1330. The eNode B can send a trace record to anEM, as in block 1340. The EM can send the trace record to a TCS, as inblock 1350.

FIGS. 14A-14C shows an exemplary embodiment of ASN programming code usedto modify a UE information response message. FIG. 14B is a continuationof the programming code in FIG. 14A. FIG. 14C is a continuation of theprogramming code in FIG. 14B. The ASN code section in FIGS. 14A-14Cdisclose ASN code for a type of CRE and a PLMN change in a UEmeasurement log, as discussed in the preceding paragraphs. Theprogramming code assumes that a signaling radio bearer is SRB1 or SRB2,a radio link control service access point (RLC-SAP) is an acknowledgedmode (AM) SAP, a logical channel is a dedicated control channel (DCCH),and the logged measurement configuration RRC message direction is from aE-UTRAN to a UE. In one embodiment, the signaling radio bearer can beSRB2 when MDT measurements are included in the UE information responsemessage.

FIGS. 15A-15C shows another exemplary embodiment of ASN programming codeused to modify a UE information response message. FIG. 15B is acontinuation of the programming code in FIG. 15A. FIG. 15C is acontinuation of the programming code in FIG. 15B. The programming codeassumes that a signaling radio bearer is SRB1 or SRB2, a radio linkcontrol service access point (RLC-SAP) is an acknowledged mode (AM) SAP,a logical channel is a dedicated control channel (DCCH), and the loggedmeasurement configuration RRC message direction is from a E-UTRAN to aUE. In one embodiment, the signaling radio bearer is SRB2 when MDTmeasurements are included in the UE information response message. TheASN code section for a CCOSONReport and a CCOSONResult represents theUEInformationResponse, as shown in FIG. 15A, and corresponds to the UEinformation response, as discussed in the preceding paragraphs for FIG.13.

Returning to FIG. 13, the UE can collect the MDT measurements in thecurrent configuration of the UE while the UE is in an RRC idle mode.When the UE returns to an RRC connected mode, the UE can indicate an MDTlog availability to the eNode B using an RRC connection setup completeRRC message. When the eNode B receives the RRC connection setup completeRRC message, the eNode B can request the MDT log by sending a UEinformation request RRC message to the UE. In one embodiment, the MDTlogs can be sent to the eNode in a UE information response RRC message.When the eNode B receives the UE information response RRC message, theeNode B can save the received MDT log(s) and create a trace record.

In one embodiment, the trace records can be sent to the TCE using a corenetwork message sequence, as shown in FIG. 13. In one embodiment, a corenetwork entity, such as the TCE, EM, or eNode B in FIG. 13, can becombined with another core network entity or reside in another corenetwork entity.

In one embodiment, a time and procedure for when the trace records aresent to the TCE can be vendor specific. In another embodiment, when thetrace session is deactivated, the trace records can be sent to the TCEwithin a selected time period, such as two hours, of the trace sessiondeactivation.

FIG. 16 shows a table of trace-based MDT reporting parameters to informa TCE about MDT measurements that were collected by a UE in a CCO SON.In one embodiment, the MDT reports for the CCO SON can be communicatedfrom the eNode B via the EM to the TCE.

Another example provides functionality 1700 of computer circuitry of aUE that is operable to connect to a 3GPP LTE cell in a cellular network,as shown in the flow chart in FIG. 17. The functionality may beimplemented as a method or the functionality may be executed asinstructions on a machine, where the instructions are included on atleast one computer readable medium or one non-transitory machinereadable storage medium. The computer circuitry can be configured torecord, at the UE, Logged MDT measurements at a selected rate when theUE is in a radio resource control (RRC) idle mode in a first LTE cell ina cellular network, as in block 1710. The computer circuitry can befurther configured to identify a change in a UE state of the RRC idlemode, as in block 1720. The computer circuitry can also be configured tostop recording the Logged MDT measurements at the UE when the UE statechanges from a camped normally UE state to another UE state of the RRCidle mode, as in block 1730. The computer circuitry can also beconfigured to resume recording of the Logged MDT measurements when theUE state changes to the camped normally UE state of the RRC idle mode,as in block 1740.

In one embodiment, the computer circuitry can be further configured tocommunicate the Logged MDT measurements to the communications network toenable the communications network to derive spatial information aboutcell boundaries in the communications network. In another embodiment,the MDT measurements are used to determine an LTE coverage hole in thecellular network. In another embodiment, the computer circuitry can befurther configured to collect the MDT measurements for a CCO SONfunction to identify the LTE coverage hole in the cellular network. Inanother embodiment, the MDT measurement includes RSRP information, RSRQinformation, Cell-Id information, location information, or time stampinformation for an inter-RAT handover.

In one embodiment, the UE state changes from the camped normally UEstate to another UE state at an inter-RAT handover from the 3GPP LTEcell to a UTRAN. In another embodiment, the computer circuitry can befurther configured to stop recording the MDT measurements at the UE whenthe UE state changes from the camped normally UE state to an any cellselection UE state or a camped on any cell UE state. In anotherembodiment, the computer circuitry can be further configured to stoprecording the MDT measurements at the UE when the UE enters a non-LTEcell, wherein the non-LTE cell is a cell in a universal terrestrialradio access network UTRAN or a cell in a global system for mobilecommunications (GSM) enhanced data rates for GSM evolution (EDGE) radioaccess network (GERAN). In another embodiment, the UE includes anantenna, a camera, a touch sensitive display screen, a speaker, amicrophone, a graphics processor, an application processor, internalmemory, or a non-volatile memory port.

FIG. 18 uses a flow chart 1800 to illustrate a method to record MDTmeasurements at a UE in a cellular network. The method can compriserecording, at the UE, Logged MDT measurements at a selected rate whenthe UE is in a RRC idle mode in a first 3GPP LTE cell in a cellular net,as in block 1810. The method can further comprise identifying a changein a UE state of the RRC idle mode, as in block 1820. The method canfurther comprise cease recording the Logged MDT measurements at the UEwhen the UE state changes from a camped normally UE state to another UEstate of the RRC idle mode, as in block 1830. The method can furthercomprise connecting the UE to an other LTE cell in the cellular network,as in block 1840. The method can further comprise resuming recording ofthe MDT measurements when the UE state changes to the camped normally UEstate of the RRC idle mode when the UE is connected to the other LTEcell, as in block 1850.

In one embodiment, the method can further comprise associating eachstate change recorded by the UE with a location stamp. In anotherembodiment, the location stamp includes global navigation satellitesystem (GNSS) information or RF fingerprint information. In anotherembodiment, the ceasing recording of the Logged MDT measurements and theresuming of the Logged MDT measurements is used by the cellular networkto derive spatial information about cell boundaries in thecommunications network. In one embodiment, the method can furthercomprise receiving, at the UE, a UE information request RRC message froman eNode B requesting the recorded MDT measurements, and sending, to theeNode B, a UE information response RRC message that includes therecorded MDT measurements. In another embodiment, the selected rate torecord Logged MDT measurements is a continuous, a semi-continuous, or aperiodic rate.

In one embodiment, the selected rate to record Logged MDT measurementsis a single measurement when the UE state changes from a camped normallyUE state to an other UE state of the RRC idle mode and a singlemeasurement when the UE state changes from the other UE state to thecamped normally UE state of the RRC idle mode. In another embodiment,the change in the UE state occurs during an inter-RAT cell reselectionby the UE. In one embodiment, the method can further comprise receiving,at the UE, a logged measurement configuration radio resource control(RRC) message from an eNode B. In another embodiment, the loggedmeasurement configuration RRC message includes CCO SON controlinformation. In another embodiment, the method can further comprisereceiving, at the UE, an inter-RAT cell reselection detection RRCmessage from an eNode B, and changing the UE state from the campednormally UE state of the RRC idle mode to the other UE state of the RRCidle mode based on the reselection detection RRC message.

FIG. 19 shows a UE 1900 for use in a communications network. The UE caninclude a cell reselection module 1910 for detecting cell re-selectionevents. The UE can also include a logging module 1920 for storing alogged minimization of drive test (MDT) record when selected cellre-selection events are detected by the cell re-selection module. In oneembodiment, the logging module can be configured to store a first LoggedMDT record at the UE when the cell re-selection module detects a firstcell re-selection event, as shown in block 1930. In one embodiment, thelogging module can be configured to store a second Logged MDT record atthe UE when the cell re-selection module detects a second cellre-selection event, as shown in block 1940. The first Logged MDT recordand the second Logged MDT record can be used to identify cell boundariesin the communications network.

In one embodiment, the first cell re-selection event is the UE movingfrom a 3GPP LTE cell to a UMTS cell and the second cell re-selectionevent is the UE moving from the UMTS cell to an other LTE cell. Inanother embodiment, the first cell re-selection event is the UE movingfrom an LTE cell to a coverage hole and the second cell re-selectionevent is the UE moving from the coverage hole to an other LTE cell. Inanother embodiment, the UE can be configured to collect the MDTmeasurements for a CCO SON function to identify the LTE coverage hole inthe cellular network. In one embodiment, the coverage hole is an areawhere a pilot signal strength is below a selected threshold value forthe UE to access the cellular network. In another embodiment, the UE canfurther comprise a receiver module 1950 for receiving a UE informationrequest from an eNode B requesting the Logged MDT record and atransmitting module 1960 for sending a UE information response thatincludes the Logged MDT record to the eNode B.

FIG. 20 provides an example illustration of the wireless device, such asa user equipment (UE), a mobile station (MS), a mobile wireless device,a mobile communication device, a tablet, a handset, or other type ofwireless device. The wireless device can include one or more antennasconfigured to communicate with a node or transmission station, such as abase station (BS), an evolved Node B (eNB), a baseband unit (BBU), aremote radio head (RRH), a remote radio equipment (RRE), a relay station(RS), a radio equipment (RE), a remote radio unit (RRU), a centralprocessing module (CPM), or other type of wireless wide area network(WWAN) access point. The wireless device can be configured tocommunicate using at least one wireless communication standard including3GPP LTE, WiMAX, High Speed Packet Access (HSPA), Bluetooth, and Wi-Fi.The wireless device can communicate using separate antennas for eachwireless communication standard or shared antennas for multiple wirelesscommunication standards. The wireless device can communicate in awireless local area network (WLAN), a wireless personal area network(WPAN), and/or a WWAN.

FIG. 20 also provides an illustration of a microphone and one or morespeakers that can be used for audio input and output from the wirelessdevice. The display screen may be a liquid crystal display (LCD) screen,or other type of display screen such as an organic light emitting diode(OLED) display. The display screen can be configured as a touch screen.The touch screen may use capacitive, resistive, or another type of touchscreen technology. An application processor and a graphics processor canbe coupled to internal memory to provide processing and displaycapabilities. A non-volatile memory port can also be used to providedata input/output options to a user. The non-volatile memory port mayalso be used to expand the memory capabilities of the wireless device. Akeyboard may be integrated with the wireless device or wirelesslyconnected to the wireless device to provide additional user input. Avirtual keyboard may also be provided using the touch screen.

Various techniques, or certain aspects or portions thereof, may take theform of program code (i.e., instructions) embodied in tangible media,such as floppy diskettes, CD-ROMs, hard drives, non-transitory computerreadable storage medium, or any other machine-readable storage mediumwherein, when the program code is loaded into and executed by a machine,such as a computer, the machine becomes an apparatus for practicing thevarious techniques. In the case of program code execution onprogrammable computers, the computing device may include a processor, astorage medium readable by the processor (including volatile andnon-volatile memory and/or storage elements), at least one input device,and at least one output device. The volatile and non-volatile memoryand/or storage elements may be a RAM, EPROM, flash drive, optical drive,magnetic hard drive, or other medium for storing electronic data. Thebase station and mobile station may also include a transceiver module, acounter module, a processing module, and/or a clock module or timermodule. One or more programs that may implement or utilize the varioustechniques described herein may use an application programming interface(API), reusable controls, and the like. Such programs may be implementedin a high level procedural or object oriented programming language tocommunicate with a computer system. However, the program(s) may beimplemented in assembly or machine language, if desired. In any case,the language may be a compiled or interpreted language, and combinedwith hardware implementations.

It should be understood that many of the functional units described inthis specification have been labeled as modules, in order to moreparticularly emphasize their implementation independence. For example, amodule may be implemented as a hardware circuit comprising custom VLSIcircuits or gate arrays, off-the-shelf semiconductors such as logicchips, transistors, or other discrete components. A module may also beimplemented in programmable hardware devices such as field programmablegate arrays, programmable array logic, programmable logic devices or thelike.

Modules may also be implemented in software for execution by varioustypes of processors. An identified module of executable code may, forinstance, comprise one or more physical or logical blocks of computerinstructions, which may, for instance, be organized as an object,procedure, or function. Nevertheless, the executables of an identifiedmodule need not be physically located together, but may comprisedisparate instructions stored in different locations which, when joinedlogically together, comprise the module and achieve the stated purposefor the module.

Indeed, a module of executable code may be a single instruction, or manyinstructions, and may even be distributed over several different codesegments, among different programs, and across several memory devices.Similarly, operational data may be identified and illustrated hereinwithin modules, and may be embodied in any suitable form and organizedwithin any suitable type of data structure. The operational data may becollected as a single data set, or may be distributed over differentlocations including over different storage devices, and may exist, atleast partially, merely as electronic signals on a system or network.The modules may be passive or active, including agents operable toperform desired functions.

Reference throughout this specification to “an example” means that aparticular feature, structure, or characteristic described in connectionwith the example is included in at least one embodiment of the presentinvention. Thus, appearances of the phrases “in an example” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as defactoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thefollowing description, numerous specific details are provided, such asexamples of layouts, distances, network examples, etc., to provide athorough understanding of embodiments of the invention. One skilled inthe relevant art will recognize, however, that the invention can bepracticed without one or more of the specific details, or with othermethods, components, layouts, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring aspects of the invention.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A user equipment (UE) operable to connect to athird generation partnership project (3GPP) long term evolution (LTE)cell in a cellular network, having computer circuitry configured to:record, at the UE, logged minimization of drive test (MDT) measurementsat a selected rate when the UE is in a radio resource control (RRC) idlemode in a first LTE cell in a cellular network; communicate the LoggedMDT measurements to a communications network to enable thecommunications network to derive spatial information about cellboundaries in the communications network; identify a change in a UEstate of the RRC idle mode; stop recording the Logged MDT measurementsat the UE when the UE state changes from a camped normally UE state toanother UE state of the RRC idle mode; and resume recording of theLogged MDT measurements when the UE state changes to the camped normallyUE state of the RRC idle mode.
 2. The computer circuitry of claim 1,wherein the MDT measurements are used to determine an LTE coverage holein the cellular network.
 3. The computer circuitry of claim 2, furtherconfigured to collect the MDT measurements for a coverage and capacityoptimization (CCO) self-organizing network (SON) function to identifythe LTE coverage hole in the cellular network.
 4. The computer circuitryof claim 1, wherein the MDT measurement includes reference signalreceived power (RSRP) information, reference signal received quality(RSRQ) information, cell identification (ID) information, locationinformation, or time stamp information for an inter-radio accesstechnology (RAT) handover.
 5. The computer circuitry of claim 1, whereinthe UE state changes from the camped normally UE state to another UEstate at an inter-radio access technology (RAT) handover from the 3GPPLTE cell to a different RAT.
 6. The computer circuitry of claim 1,further configured to stop recording the MDT measurements at the UE whenthe UE state changes from the camped normally UE state to an any cellselection UE state or a camped on any cell UE state.
 7. The computercircuitry of claim 6, further configured to stop recording the MDTmeasurements at the UE when the UE enters a non-LTE cell, wherein thenon-LTE cell is a cell in a universal terrestrial radio access network(UTRAN) or a cell in a global system for mobile communications (GSM)enhanced data rates for GSM evolution (EDGE) radio access network(GERAN).
 8. The computer circuitry of claim 1, wherein the UE includesan antenna, a camera, a touch sensitive display screen, a speaker, amicrophone, a graphics processor, an application processor, internalmemory, or a non-volatile memory port.
 9. A method to recordminimization of drive test (MDT) measurements at a user equipment (UE)in a cellular network, comprising: recording, at the UE, loggedminimization of drive test (MDT) measurements at a selected rate whenthe UE is in a radio resource control (RRC) idle mode in a first thirdgeneration partnership project (3GPP) long term evolution (LTE) cell ina cellular network; identifying a change in a UE state of the RRC idlemode; cease recording the Logged MDT measurements at the UE when the UEstate changes from a camped normally UE state to another UE state of theRRC idle mode; connecting the UE to another LTE cell in the cellularnetwork; and resuming recording of the MDT measurements when the UEstate changes to the camped normally UE state of the RRC idle mode whenthe UE is connected to the other LTE cell, wherein the ceasing recordingof the Logged MDT measurements and the resuming of the Logged MDTmeasurements is used by the cellular network to derive spatialinformation about cell boundaries in a communications network.
 10. Themethod of claim 9, further comprising associating each state changerecorded by the UE with a location stamp.
 11. The method of claim 10,wherein the location stamp includes global navigation satellite system(GNSS) information or radio frequency (RF) fingerprint information. 12.The method of claim 9, further comprising: receiving, at the UE, a UEinformation request radio resource control (RRC) message from an evolvedNode B (eNode B) requesting the recorded MDT measurements; and sending,to the eNode B, a UE information response RRC message that includes therecorded MDT measurements.
 13. The method of claim 9, wherein theselected rate to record Logged MDT measurements is a continuous, asemi-continuous, or a periodic rate.
 14. The method of claim 9, whereinthe selected rate to record Logged MDT measurements is a singlemeasurement when the UE state changes from a camped normally UE state toan other UE state of the RRC idle mode and a single measurement when theUE state changes from the other UE state to the camped normally UE stateof the RRC idle mode.
 15. The method of claim 9, wherein the change inthe UE state occurs during an inter radio access technology (RAT) cellreselection by the UE.
 16. The method of claim 9, further comprisingreceiving, at the UE, a logged measurement configuration radio resourcecontrol (RRC) message from an evolved node B (eNode B).
 17. The methodof claim 16, wherein the logged measurement configuration RRC messageincludes coverage and capacity optimization (CCO) self-organizingnetwork (SON) control information.
 18. The method of claim 9, furthercomprising: receiving, at the UE, an inter radio access technology (RAT)cell reselection detection radio resource control (RRC) message from anevolved node B (eNode B); and changing the UE state from the campednormally UE state of the RRC idle mode to the other UE state of the RRCidle mode based on the reselection detection RRC message.
 19. A userequipment (UE) for use in a communications network, the UE comprising: acell reselection module for detecting cell re-selection events; and alogging module for storing a logged minimization of drive test (MDT)record when selected cell re-selection events are detected by the cellre-selection module, the logging module further configured to: store afirst Logged MDT record at the UE when the cell re-selection moduledetects a first cell re-selection event; and store a second Logged MDTrecord at the UE when the cell re-selection module detects a second cellre-selection event, wherein the first Logged MDT record and the secondLogged MDT record are used to identify cell boundaries in thecommunications network.
 20. The UE of claim 19, wherein the first cellre-selection event is the UE moving from an third generation partnershipproject (3GPP) long term evolution (LTE) cell to a universal mobiletelecommunications system (UMTS) cell and the second cell re-selectionevent is the UE moving from the UMTS cell to an other LTE cell.
 21. TheUE of claim 19, wherein the first cell re-selection event is the UEmoving from an LTE cell to a coverage hole and the second cellre-selection event is the UE moving from the coverage hole to an otherLTE cell.
 22. The UE of claim 21, further configured to collect the MDTmeasurements for a coverage and capacity optimization (CCO)self-organizing network (SON) function to identify the LTE coverage holein the cellular network.
 23. The UE of claim 21, wherein the coveragehole is an area where a pilot signal strength is below a selectedthreshold value for the UE to access the cellular network.
 24. The UE ofclaim 19, further comprising: a receiver module for receiving a UEinformation request from an evolved Node B (eNode B) requesting theLogged MDT record; and a transmitting module for sending a UEinformation response that includes the Logged MDT record to the eNode B.